Motion enable mechanism with capacitive sensor

ABSTRACT

A motion-enable device includes a mechanical switch and a capacitive sensor with a sensing region that is located adjacent to the mechanical switch. The mechanical switch enables a first signal when closed or actuated that indicates that the mechanical switch is in an active state. The capacitive sensor enables a second signal when a conductive object is disposed in the sensing region, where the second signal indicates that the capacitive sensor is in an active state. Enablement of operation of an apparatus depends on receipt of both the first signal and the second signal. The mechanical switch and the capacitive sensor act as the two separate switches required by functional safety requirements for a motion enable device. Because the sensing region of the capacitive sensor is adjacent to the mechanical switch, the first and second signals are generated when an operator actuates the mechanical switch with a single digit.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims the benefit of U.S. ProvisionalApplication No. 62/566,301, filed Sep. 29, 2017. The aforementioned U.S.Provisional Application, including any appendices or attachmentsthereof, is hereby incorporated by reference in its entirety.

BACKGROUND

Unless otherwise indicated herein, the approaches described in thissection are not prior art to the claims in this application and are notadmitted to be prior art by inclusion in this section.

The motion enable switch (also referred to as a “dead man's switch) is aform of fail-safe device designed to stop the motion or operation of amachine in the absence of an active input from an operator. Motionenable switches are typically employed in situations in which unwantedmotion of a mechanism can present a crush hazard or other dangeroussituation to the operator or nearby persons. For example, in radiationtherapy and medical imaging applications, a patient is preciselypositioned for treatment or imaging via a movable couch, and a motionenable switch must be continuously depressed by the operator for couchmotion to take place. Thus, couch motion only occurs while beingobserved and actively enabled by the operator, which greatly reduces therisk of patient collisions.

An additional functional safety requirement associated with some motionenable devices is the inclusion of two separate switches in the motionenable device, where motion is only enabled by the device when bothswitches are actively actuated by an operator. In radiation therapy andmedical imaging applications, two adjacent mechanical buttons are oftenemployed as the two separate switches of the motion enable device, andthe operator depresses both buttons to cause the couch motion thatpositions a patient for treatment. One drawback to this approach isthat, when positioning a patient, an operator is required to cock thewrist at an awkward angle while exerting significant pressure on thebuttons. This is particularly true when the control interface isconfigured as a side panel or other vertical surface. Because thisphysically awkward operation may be performed dozens or hundreds oftimes per day, the operator can be susceptible to one or more repetitivestress injuries, such as carpal tunnel syndrome. Another drawback of thetwo mechanical button approach for motion enable of an apparatus is thatif one of the two mechanical buttons has failed in the closed position,the potentially hazardous motion of the apparatus will be unexpectedlyenabled the single functioning button is depressed, which violates thefunctional safety standards developed by the InternationalElectrotechnical Commission (IEC). Further, detection of such a failurecan be problematic, since motion of the device will appear to be enablednormally, by depressing two mechanical buttons, until unexpected motionoccurs when only the single functioning button is depressed.

In light of the above, there is a need in the art for a motion enablesystem that addresses the above-described challenges.

BRIEF DESCRIPTION OF THE DRAWINGS

Features of the present disclosure will become more fully apparent fromthe following description and appended claims, taken in conjunction withthe accompanying drawings. These drawings depict only severalembodiments in accordance with the disclosure and are, therefore, not tobe considered limiting of its scope. The disclosure will be describedwith additional specificity and detail through use of the accompanyingdrawings.

FIG. 1 schematically illustrates a motion enable system, according tovarious embodiments of the present disclosure.

FIG. 2 is a schematic cross-sectional view of motion enable device,according to various embodiments of the present disclosure.

FIG. 3 is a schematic cross-sectional view of a motion enable device,according to various embodiments of the present disclosure.

FIG. 4 schematically illustrates a user interface panel that includes aplurality of motion enable devices, according to an embodiment of thepresent disclosure.

FIG. 5 schematically illustrates an operator hand depressing a verticaldown button on a user interface panel, according to an embodiment of thepresent disclosure.

FIG. 6 is a schematic cross-sectional view of a motion enable devicethat generates an outer capacitive sensing region and an innercapacitive sensing region, according to various embodiments of thepresent disclosure.

FIG. 7 illustrates a state diagram for the motion enable system in FIG.1, according to various embodiments of the present disclosure.

FIG. 8 sets forth a flowchart summarizing an example method for enablingthe motion tracking of an actuator, according to one or more embodimentsof the present disclosure.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings, which form a part hereof. In the drawings,similar symbols typically identify similar components, unless contextdictates otherwise. The illustrative embodiments described in thedetailed description, drawings, and claims are not meant to be limiting.Other embodiments may be utilized, and other changes may be made,without departing from the spirit or scope of the subject matterpresented here. It will be readily understood that the aspects of thedisclosure, as generally described herein, and illustrated in thefigures, can be arranged, substituted, combined, and designed in a widevariety of different configurations, all of which are explicitlycontemplated and make part of this disclosure.

As noted above, the use of two adjacent mechanical buttons in a motionenable device can result in repetitive stress injuries in an operator.According to various embodiments, a motion-enable device includes amechanical switch, such as a button mechanism, and a capacitive sensorwith a sensing region that is located adjacent to the mechanical switch.The mechanical switch is configured to enable a first signal when closedor actuated, where the first signal indicates that the mechanical switchis in an active state. The capacitive sensor is configured to enable asecond signal when a conductive object (such as a digit of an operator)is disposed in the sensing region, where the second signal indicatesthat the capacitive sensor is in an active state. Enablement ofoperation or motion of an apparatus depends on receipt of both the firstsignal and the second signal. As a result, the mechanical switch and thecapacitive sensor effectively act as the two separate switches requiredby the IEC functional safety requirements for a motion enable device.Because the sensing region of the capacitive sensor is adjacent to themechanical switch, the first and second signals are generated when anoperator actuates the mechanical switch with a single digit orconductive object. Thus, operation or motion of the apparatus is enabledwhen an operator actuates the mechanical switch with a single digit.

FIG. 1 schematically illustrates a motion enable system 100, accordingto various embodiments of the present disclosure. Motion enable system100 includes a controller 110, a motion enable device 120, and a powerenable switch 130, and is configured to prevent unintended operation ofor motion associated with a particular apparatus. In the embodimentillustrated in FIG. 1, the particular apparatus includes a motor drivercircuit 150. In addition, motion enable system 100 is configured toenable operation of or motion associated with motor driver circuit 150when an operator actively actuates a mechanical switch included inmotion enable device 120. In other embodiments, motor driver circuit 150can be any technically feasible actuator that can be controlled bycontroller 110 to produce an output motion.

Controller 110 controls the operation of motion enable system 100,including receiving a mechanical switch active signal 101 and acapacitive sensor active signal 102 from motion enable device 120 and,when certain conditions are met, transmitting a power enable signal 103to power enable switch 130. For example, in some embodiments, controller110 transmits power enable signal 103 to power enable switch 130 when acapacitive sensor of motion enable device 120 is active, as describedbelow. In addition, controller 110 transmits one or more control signals104 to motor driver circuit 150 that include motion inputs for atargeted motion of the apparatus associated with motor driver circuit150, typically in response to a physical input from an operator viamotion enable device 120. For example, in some embodiments, controller110 transmits one or more control signals 104 to motor driver circuit150 when an operator depresses or otherwise actuates a mechanical switch121 included in motion enable device, as described below. Generally,controller 110 transmits the one or more control signals 104 to motordriver circuit 150 when certain conditions are met, such as the receiptof mechanical switch active signal 101 and a capacitive sensor activesignal 102. In some embodiments, controller 110 includes a processor 111and a memory 112.

Processor 111 is communicatively coupled to memory 112 and/or anon-volatile data storage medium such as a solid-state drive (SSD).Processor 111 may be any suitable processor implemented as a CPU, anapplication-specific integrated circuit (ASIC), a field programmablegate array (FPGA), any other type of processing unit, or a combinationof different processing units. In general, processor 111 may be anytechnically feasible hardware unit capable of processing data and/orexecuting software applications residing in memory 112 or in firmware(not shown). Processor 111 is configured to read data from and writedata to memory 112 and/or firmware. Memory 112 may include a randomaccess memory (RAM) module, a flash memory unit, any other type ofmemory unit, or a combination thereof. Memory 112 may be used for datastorage, and may include various software programs that can be executedby processor 111 and application data associated with said softwareprograms. For example, in some embodiments, controller 110 includes amotion control supervisor 115 that can be implemented as a softwareprogram executed by processor 111 and/or as firmware (not shown)included in controller 110. In such embodiments, motion controlsupervisor 115 is responsible for generating appropriate control signals104 to cause a targeted motion trajectory of a motor (not shown) orother actuator included in motor driver circuit 150. In the embodimentillustrated in FIG. 2, memory 112 is depicted as a separate device fromprocessor 111, but in other embodiments memory 112 can be included inprocessor 111.

Power enable switch 130 is configured to selectively enable a powerconnection 109 from a power source 140 to motor driver circuit 150, inresponse to receiving power enable signal 103 from controller 110. Insome embodiments, power enable switch 130 is an electronic circuit orfirmware switch, rather than a mechanical switch. In such embodiments,power enable switch 130 can be implemented as part of controller 110 oras a separate entity.

Motor driver circuit 150 is configured to generate a physical output ofan apparatus associated with motor driver circuit 150, such as atargeted motion of the apparatus. For example, in some embodiments,motor driver circuit 150 includes a motor for positioning a patientcouch of a radiation therapy system along one axis of motion, forexample a longitudinal axis, a lateral axis, or a vertical axis. Assuch, when power connection 109 to power source 140 is enabled and motordriver circuit 150 has received one or more control signals 104 fromcontroller 110, control signals 104 cause the motor of motor drivercircuit 150 to generate a suitable output motion. In some embodiments,control signals 104 can be any technically feasible control signal thatcan be used to control the output motion of motor driver circuit 150,including an analog signal, a digital signal, a serial signal, apulse-width modulated signal, and the like.

Motion enable device 120 includes a mechanical switch 121 and acapacitive sensor 122. In some embodiments, motion enable device 120 isconfigured so that, when an operator provides an active input tomechanical switch 121, capacitive sensor 122 becomes active beforemechanical switch 121 becomes active. Thus, in such embodiments, whenthe operator provides the active input to mechanical switch 121,capacitive sensor 122 generates, enables, and/or transmits capacitiveswitch active signal 102 before mechanical switch 121 generates,enables, and/or transmits mechanical switch active signal 101.Alternatively, in some embodiments, motion enable device 120 isconfigured so that, when an operator provides an active input tomechanical switch 121, capacitive sensor 122 becomes active atsubstantially the same time that mechanical switch 121 becomes active.

Mechanical switch 121 can be any technically feasible device orapparatus that, when actuated from a first position to a secondposition, enables mechanical switch active signal 101. For example, insome embodiments, mechanical switch 121 includes a button mechanism thatremains in an open or inactive position except when actively depressed,for example by a spring-return mechanism or elastic member. In suchembodiments, when the button mechanism of mechanical switch 121 isdepressed and is in a closed or active position, an electricalconnection is created that enables mechanical switch active signal 101and/or causes transmission of mechanical switch active signal 101 tocontroller 110. Conversely, when the button mechanism of mechanicalswitch 121 stops being depressed by the operator, the spring-returnmechanism or elastic member returns mechanical switch 121 to the openposition. In another such embodiment, mechanical switch 121 includes atwo-position toggle switch, or any other two-position switch mechanismthat can be configured to remains in an open or inactive position exceptwhen actively depressed and returns to the open or inactive positionwhen no longer depressed.

Capacitive sensor 122 can be any technically feasible capacitive sensorconfigured to enable capacitive sensor active signal 102 and/or transmitcapacitive active sensor signal 102 to controller 110 when a user digitor other conductive object is detected in a sensing region (not shown inFIG. 1) of capacitive sensor 122. For example, in some embodiments,capacitive sensor 122 includes a projected capacitance device with asensing region. In such embodiments, when a conductive object enters thesensing region, such as a digit of an operator or a conductive stylus,capacitive sensor 122 detects the presence of the conductive objectbefore the conductive object contacts a surface of capacitive sensor122. Capacitive sensor 122 can be configured for use with any suitableconductive object, including a single digit of an operator, an activeconductive stylus, a passive conductive stylus, and the like. In someembodiments, capacitive sensor 122 is configured as a mutual capacitivesensor, and in other embodiments capacitive sensor 122 is configured asa self-capacitive sensor. Furthermore, capacitive sensor 122 can includeany other technically feasible capacitive sensor that can detect thepresence of a conductive member in the sensing region of capacitivesensor 122.

In some embodiments, capacitive sensor 122 includes variouscapacitance-sensing electronics 123, such as a single capacitive sensorelement or an array of capacitive sensor elements that generate theelectric field forming the sensing region of capacitive sensor 102.Capacitance-sensing electronics 123 may further include an excitationsource couple to the capacitive sensor element(s) for refreshing theelectric field, a capacitance-to-digital converter, and/or compensationcircuitry for ensuring accurate capacitance detection in differentconditions. In some embodiments, capacitance-sensing electronics furtherincludes logic, such as firmware or locally-executed software that 1)determines whether a change in field strength measured by thecapacitance-to-digital converter corresponds to a conductive objectentering the sensing region of capacitive sensor 102, and 2) transmitscapacitive sensor active signal 102 when appropriate. Alternatively, insome embodiments, such logic can reside in controller 110, andcapacitive sensor active signal 102 then includes an analog or digitalsignal that is based on a change in field strength measured by thecapacitance-to-digital converter.

In some embodiments, capacitive sensor 122 is configured with a sensingregion that is adjacent to or extends past an interface surface ofmechanical switch 121. Thus, in such embodiments, when an operatorperforms a physical input using mechanical switch 121 with a conductiveobject, the conductive object enters the sensing region of capacitivesensor 122 before reaching the interface surface of mechanical switch121. As a result, motion enable device 120 is configured to generate orenable capacitive sensor active signal 102 prior to generating orenabling mechanical switch active signal 101. One such embodiment isillustrated in FIG. 2.

FIG. 2 is a schematic cross-sectional view of motion enable device 120,according to various embodiments of the present disclosure. Motionenable device 120 includes a button 210 with an interface surface 201that is recessed from a surrounding surface 202 of motion enable device120 by a recess distance 203. Recess distance 203 prevents accidentalcontact with motion enable device 120 from causing button 210 to bedepressed, such via unintended contact with an elbow or shoulder. Recessdistance 203 can be any suitable distance that reduces the likelihood ofunintended contact with interface surface 201. Thus, for buttons 210that are relatively large, recess distance 203 can be greater than forbutton 210 that are relatively small.

Motion enable device 120 is configured to enable mechanical switchactive signal 101 when actuated (or depressed) from an open position toa closed position. In the embodiment illustrated in FIG. 2, motionenable device 120 enables mechanical switch active signal 101 by closingan electrical circuit between a first conductive contact or trace 211and a second conductive contact or trace 212 when button 210 isdepressed. Motion enable device 120 can be configured with anytechnically feasible button mechanism that closes the electrical circuitbetween first conductive contact or trace 211 and second conductivecontact or trace 212. In some embodiments, button 210 includes a bulkregion 204 that is at least partially formed from an elastic material,such as silicone rubber, and a compressible projection 205 that includesa material that increases in electrical conductivity when compressed,such as silicone rubber with conductive carbon particles suspendedtherein. In such embodiments, when button 210 is depressed by aconductive member, compressible projection 205 is compressed, theconductive particles suspended within compressible projection 205 comeinto contact with each other, and the flow of electricity between firstconductive contact or trace 211 and second conductive contact or trace212 is enabled.

Motion enable device 120 is further configured to enable capacitivesensor active signal 102 when a conductive member is disposed within acapacitive sensing region 220. To that end, motion enable device 120includes a capacitive sensor 206 configured to generate capacitivesensing region 220. In embodiments in which capacitive sensing region220 extends beyond interface surface 201 of button 210, motion enabledevice 120 enables capacitive sensor active signal 102 when a conductiveobject enters capacitive sensing region 220 and before button 210 isdepressed or actuated into the active position. Thus, in suchembodiments, when an operator initiates an input via motion enabledevice 120, motion enable device 120 is configured to enable capacitivesensor active signal 102 before enabling mechanical switch active signal101. In some embodiments, capacitive sensing region 220 extends past theinterface surface by at least about 2 mm, but no more than about 20 mm,to prevent unintended enablement or transmission of capacitive sensoractive signal 101 when an operator is proximate motion enable device 120but is not performing a physical input to motion enable device 120.

In some embodiments, a capacitive sensor included in a motion enabledevice is associated with multiple mechanical switches. One suchembodiment is illustrated in FIG. 3. FIG. 3 is a schematiccross-sectional view of a motion enable device 300, according to variousembodiments of the present disclosure. Motion enable device 300 issubstantially similar in configuration to motion enable device 120 inFIG. 2, except that motion enable device 300 includes a singlecapacitive sensor 306 that is associated with multiple buttons 310A and310B. As shown, capacitive sensor 306 is configured to generate acapacitive sensing region 320 that extends beyond an interface surface301A of button 310A and interface surface 301B of button 310B.

In some embodiments, buttons 310A and 310B make up a pair of inputcontrol buttons associated with a particular axis of motion of anapparatus. For example, in an embodiment in which buttons 310A and 310Bare associated with a vertical axis of motion of a patient couch in aradiation therapy system, button 310A controls motion of the patientcouch in the upward direction and button 310B controls motion of thepatient couch in the downward direction. Thus, when an operator moves adigit or other conductive object within capacitive sensing region 320,power connection 109 is enabled via a power enable switch (such as powerenable switch 130) between a power source (such as power source 140) anda motor driver circuit associated with moving the patient couch alongthe vertical axis of motion (such as motor driver circuit 150 in FIG.1). One such embodiment is illustrated in FIG. 4.

FIG. 4 schematically illustrates a user interface panel 400 thatincludes a plurality of motion enable devices, according to anembodiment of the present disclosure. User interface panel 400 includesmultiple mechanical buttons 401 that each control motion of a patientcouch or other apparatus along one or more axes of motion. For example,the one or more axes of motion can include a vertical, a lateral, and alongitudinal axis of motion. In one such embodiment, a portion ofbuttons 401 are configured to initiate preprogrammed motion of a patientcouch for a radiation therapy (RT) system along one or more of theseaxes, while other buttons 401 enable manual or preprogrammed control ofthe patient couch along a single axis of motion. In the embodimentillustrated in FIG. 4, user interface panel 400 includes an alignmentbutton 411 that moves the patient couch to a virtual iso-center of theassociated RT system, a vertical up button 412 for raising the patientcouch, a vertical down button 413 for lowering the patient couch, alongitudinal in button 414 for moving the patient couch into the bore ofthe RT system, a longitudinal out button 415 for moving the patientcouch out of the bore of the RT system, a lateral left button 416 formoving the patient couch to the left relative to the bore, a lateralright button 417 for moving the patient couch to the right relative tothe bore, a load button 418 for moving the patient couch to thegeometric iso-center of the RT system, and a home button 419 forunloading a patient, i.e., for moving the patient couch to a homeposition of the RT system. In some embodiments, user interface panel 400includes more mechanical buttons 401 or fewer mechanical buttons 401than those shown in FIG. 4.

Each of mechanical buttons 401 is associated with a capacitive sensor,and together with the associated capacitive sensor forms a motion enabledevice substantially similar to motion enable device 120, describedabove. Some of mechanical buttons 401 are associated with a singlecapacitive sensor. For example, in the embodiment illustrated in FIG. 4,alignment button 411, load button 418, and home button 419 are eachassociated with a single capacitive sensor 406. Alternatively oradditionally, certain pairs of mechanical buttons 401 are associatedwith a single capacitive sensor. For example, in the embodimentillustrated in FIG. 4, vertical up button 412 and vertical down button413 are both associated with a single capacitive sensor 407,longitudinal in button 414 and longitudinal out button 415 are bothassociated with a single capacitive sensor 408, and lateral left button416 and lateral right button 417 are both associated with a singlecapacitive sensor 409.

In some embodiments, some of mechanical buttons 401 are configured asmanual motion buttons that initiate motion of the patient couch in aparticular direction. For example, in the embodiment illustrated in FIG.4, manual motion buttons include vertical up button 412, vertical downbutton 413, longitudinal in button 414, longitudinal out button 415,lateral left button 416, and lateral right button 417. In someembodiments, some of mechanical buttons 401 are configured to initiatespecific preprogrammed motions along one or more axes of motion. Forexample, in the embodiment illustrated in FIG. 4, preprogrammed motionbuttons include alignment button 411, load button 418, and home button419. It is noted that both manual motion buttons and preprogrammedmotion buttons are generally configured to be part of a motion enabledevice similar to motion enable device 120 of FIG. 1.

User interface panel 400 enables an operator to perform manual inputs toinitiate manual positioning and/or preprogrammed positioning of apatient couch (not shown), such as a patient couch of an RT system. Userinterface panel 400 may be located on a vertical surface 402 proximatethe patient couch, for example on a stand and/or a vertical paneladjacent to the bore of the RT system. Alternatively, user interfacepanel 400 can be located on a hand-held control pendant that iscommunicatively connected with via a wired and/or wireless connection toa control system that receives inputs from the control pendant, such ascontroller 110.

When user interface panel 400 is so located, an operator can performmanual inputs into user interface panel 400 without bending or lookingdown. Further, for each motion enable device included in user interfacepanel 400, the operator can activate the two separate devices includedtherein with a single digit or conductive stylus. That is, the operatorcan activate both the mechanical switch and the capacitive sensor of aparticular motion enable device by depressing the mechanical switch ofthat particular motion enable device with a single digit or conductiveobject, which is much more ergonomic than pressing two mechanicalswitches with two different digits, as illustrated in FIG. 5.

FIG. 5 schematically illustrates an operator hand 501 depressingvertical down button 413, according to an embodiment of the presentdisclosure. As shown, the operator can employ a single digit 502 todepress vertical down button 413 to enable motion of the patient couchvertically downward. As a result, the operator can keep wrist 503straight while performing the targeted manual input into user interfacepanel 400. Therefore, as shown in FIG. 5, when continuously depressingany of mechanical buttons 401, such as vertical down button 413, theoperator is at significantly reduced risk of repetitive stress injuries.Thus, the operator can perform manual inputs via user interface panel400 safely and comfortably.

In some embodiments, a capacitive sensor included in a motion enabledevice is configured with an outer capacitive sensing region and aninner capacitive sensing region, thereby enabling activation of thecapacitive sensor when a conductive object enters a first smallersensing region and deactivation of the capacitive sensor when theconductive object exits a second larger sensing region. One suchembodiment is illustrated in FIG. 6. FIG. 6 is a schematiccross-sectional view of a motion enable device 600 that generates anouter capacitive sensing region 620 and an inner capacitive sensingregion 630, according to various embodiments of the present disclosure.Motion enable device 600 is substantially similar in configuration tomotion enable device 120 in FIG. 2, except that motion enable device 600is configured with a capacitive sensor 622 that generates outercapacitive sensing region 620 and inner capacitive sensing region 630.In addition, motion enable device 600 is configured to transmit a firstcapacitive sensor active signal 602A when a user digit or otherconductive object is detected in outer capacitive sensing region 620 anda second capacitive sensor active signal 602B when the user digit orother conductive object is detected in inner capacitive sensing region630. In such embodiments, controller 110 can therefore determine whethera conductive object is within outer capacitive sensing region 620 orinner capacitive sensing region 630.

According to some embodiments, controller 110 changes capacitive sensor622 from inactive to active when capacitive sensor 622 is currentlyinactive and a conductive object is detected within inner capacitivesensing region 630. By contrast, in such embodiments, controller 110changes capacitive sensor 622 from active to inactive when capacitivesensor 622 is currently active and the conductive object is not detectedwithin either inner capacitive sensing region 630 or outer capacitivesensing region 620. As a result, if an operator hovers a conductiveobject near motion enable switch 600, capacitive sensor 622 does notrepeatedly change from active to inactive, as the conductive objectenters and exits the capacitive sensing region. Instead, the operatorwould have to move the conductive object within inner capacitive sensingregion 620, then out of outer capacitive sensing region 630 forcontroller 110 to change back to inactive. As a result, in suchembodiments, transmission of power enable signal 103 to power enableswitch 130 is not repeatedly initiated and then stopped when theoperator hovers a conductive object near motion enable switch 600.

FIG. 7 illustrates a state diagram 700 for motion enable system 100 inFIG. 1, according to various embodiments of the present disclosure. Inthe embodiment illustrated in FIG. 7, motion enable system 100 operatesin five different power states: a Power Off state 701, a Power On state702, a Motion Enable state 703, a Ramp Down state 704, and a Fast RampDown state 705. However, in other embodiments, motion enable system 100can operate in additional states or in fewer states than those shown inFIG. 7.

In Power Off state 701, there is no power connection 109 between powersource 140 and motor driver circuit 150, and the actuator associatedwith or included in motor driver circuit 150 cannot produce an outputmotion. Generally, when capacitive sensor 122 is inactive (no conductiveobject detected, denoted by C in FIG. 4) and mechanical switch 121 isinactive (not depressed/in open position, denoted by B in FIG. 4),motion enable system 100 is in Power Off state 701. In some embodiments,motion enable system 100 enters Power Off state 701 based on a decisionby motion control supervisor 115, such as when a preprogrammed motionhas been completed by an actuator associated with motor driver circuit150. Alternatively or additionally, in some embodiments, motion enablesystem 100 enters Power Off state 701 when a fast ramp-down timer thatis initiated in Ramp Down state 704 expires. The fast ramp-down timer isdescribed below in conjunction with Ramp Down state 704.

In Power On state 702, power connection 109 is established between powersource 140 and motor driver circuit 150. Generally, when controller 110receives capacitive sensor active signal 102 from motion enable device120 (i.e., a conductive object is detected and capacitive sensor 122 isactive, denoted by C in FIG. 4), controller 110 transmits power enablesignal 103 to power enable switch 130, and motion enable system 100enters Power On state 702. In Power On state 702, the components ofmotor driver circuit 150 can begin powering up even though no controlsignals 104 have been received from controller 110. Thus, Power On state702 allows motor drive circuit 150 to be prepared for operation beforeboth switches of motion enable device 120 (i.e., mechanical switch 121and capacitive sensor 122) have become active. As shown, in theembodiment illustrated in FIG. 7, when motion enable system 100 is inPower On state 702, controller 110 continuously confirms that mechanicalswitch 121 is inactive (i.e., mechanical switch active signal 101 hasnot been received from mechanical switch 121) and capacitive sensor 122is active (i.e., capacitive sensor active signal 102 is being receivedfrom capacitive sensor 122).

In Motion Enable state 703, motor driver circuit 150 is powered andmotion control supervisor 115 transmits any appropriate control signals104 to motor driver circuit 150 to cause a targeted motion trajectory ofa motor or other actuator included in motor driver circuit 150. In someembodiments, motion enable system 100 enters Motion Enable state 703 inresponse to controller 110 receiving or detecting mechanical switchactive signal 101 and capacitive sensor active signal 102. That is,motion enable system 100 enters Motion Enable state 703 when aconductive object is detected (capacitive sensor 122 is active) andmechanical switch 121 is actuated and becomes active.

In some embodiments, upon entering Motion Enable state 703, motioncontrol supervisor 115 determines whether there are any faults thatprevent motion driver circuit from generating an output motion. If nofaults are detected, motion control supervisor 115 then determines atarget trajectory of the output motion of motor driver circuit 150, andtransmits control signals 104 to motor driver circuit 150 suitable forcausing the motor or actuator to generate the output motion that followsthe targeted velocity profile.

In some embodiments, the target trajectory may include an S-curveacceleration profile for reducing or eliminating jerk. Alternatively oradditionally, in some embodiments the target trajectory may include aconstant output motion of motor driver circuit 150. In such embodiments,motion control supervisor 115 determines the target trajectory inresponse to an operator continuously depressing the mechanical switch121 of motion enable device 120, or continuously performing any othersuitable physical input with the mechanical switch 121. For example,when motor driver circuit 150 is associated with or includes a motor forpositioning a patient couch longitudinally in an RT system, when anoperator continuously depresses longitudinal in button 414 (shown inFIG. 4), motion control supervisor 115 transmits control signals 104 tomotor driver circuit 150 that cause the motor to actuate the patientcouch with a targeted velocity profile that includes an initial S-curveacceleration profile, then move at an initial longitudinal velocity.After the operator has depressed longitudinal in button 414 for longerthat a specified time period (e.g., three seconds), motion controlsupervisor 115 then ramps the velocity to a higher longitudinalvelocity.

In embodiments in which the operator provides a physical input to amotion enable device 120 that is associated with a preprogrammed motion,such as alignment button 411, load button 418, or home button 419 inFIG. 4, the target trajectory may further terminate with an S-curvedeceleration profile for reducing or eliminating jerk. In suchembodiments, motion control supervisor 115 generally stops sending anycontrol signals 104 to motor driver circuit 150 once the preprogrammedmotion is completed, even when controller 110 determines that capacitivesensor 122 and mechanical switch 121 are both active.

In Motion Enable state 703, when controller 110 determines thatcapacitive sensor 122 is active and mechanical switch 121 is not active,motion enable system 100 enters Ramp Down state 704. That is, when anoperator stops depressing mechanical switch 121 with a conductive object(such as a digit or conductive stylus), but the conductive object isstill within the capacitive sensing region of capacitive sensor 122,motion enable system 100 enters Ramp Down state 704.

In Ramp Down state 704, one of the two switches of motion enable device120 is not active, and therefore motion of the motor or other actuatorassociated with motor driver circuit 150 should stop. In someembodiments, when motion enable system 100 enters Ramp Down state 704,motion control supervisor 115 determines a target trajectory for themotor or other actuator associated with motor driver circuit 150, andtransmits control signals 104 to motor driver circuit 150 suitable forcausing the motor or actuator to generate the output motion that followsthe targeted velocity profile. In some embodiments the target trajectorymay include an S-curve deceleration profile that minimizes or eliminatesjerk. Thus, in Ramp Down state 704, when an operator stops depressing oractuating mechanical switch 121 of motion enable device 120, controller110 stops the output motion of motor driver circuit 150 according to asmooth deceleration curve.

In some embodiments, while motion enable system 100 is in Ramp Downstate 704, controller 110 initiates a fast ramp-down timer. Uponexpiration of the fast ramp-down timer, controller 110 stops sendingpower enable signal 103 to power enable switch 130, and motor controlcircuit 150 is not longer powered. In some embodiments, the fastramp-down timer is on the order of about 500 ms to about two seconds.

In Ramp Down state 704, when controller 110 determines that capacitivesensor 122 is not active and mechanical switch 121 is also not active,motion enable system 100 enters Fast Ramp Down state 705. That is, whenan operator stops depressing mechanical switch 121 with a conductiveobject (such as a digit or conductive stylus) and the conductive objectis also no longer within the capacitive sensing region of capacitivesensor 122, motion enable system 100 enters Fast Ramp Down state 705.

In Fast Ramp Down state 705, the two switches of motion enable device120 are both inactive, and therefore motion of the motor or otheractuator associated with motor driver circuit 150 should stop within adistance that satisfies an IEC stopping distance for the actuator ormotor associated with motor driver circuit 150. In some embodiments,when motion enable system 100 enters Fast Ramp Down state 705, motioncontrol supervisor 115 determines a target trajectory for the motor orother actuator associated with motor driver circuit 150, and transmitscontrol signals 104 to motor driver circuit 150 suitable for causing themotor or actuator to generate the output motion that follows thetargeted velocity profile. The target trajectory generally includes afast deceleration profile that satisfies an IEC stopping distance forthe actuator or motor associated with motor driver circuit 150. Thus, inFast Ramp Down state 705, when an operator stops depressing mechanicalswitch 121 with a conductive object and removes the previously detectedconductive object from the capacitive sensing region of capacitivesensor 122, controller 110 stops the output motion of motor drivercircuit 150 quickly. That is, motion enable system 100 enters Fast RampDown state 705 in response to the operator completely removing the digitor conductive stylus that was previously depressing the mechanicalswitch of motion enable device 120. In this way, an operator can causecontroller 110 to initiate a fast ramp-down of the output motion ofmotor driver circuit 150 to avoid a collision, rather than a smootherbut slower ramp-down of the output motion of motor driver circuit 150.

It is noted that in some embodiments, when motion enable system 100enters Fast Ramp Down state 705, rather than removing power connection109 to motor driver circuit 150 so that a motor or actuator coasts to astop, motor driver circuit 150 is employed to actively decelerate themotor or actuator so that the output motion of motor driver circuit 150is less than or equal to an IEC stopping distance.

In some embodiments, while motion enable system 100 is in Fast Ramp Downstate 705, controller 110 continues the fast ramp-down timer. Uponexpiration of the fast ramp-down timer, controller 110 stops sendingpower enable signal 103 to power enable switch 130, motor controlcircuit 150 is not longer powered, and motion enable system 100 entersPower Off state 701.

FIG. 8 sets forth a flowchart summarizing an example method for enablingthe motion tracking of an actuator, according to one or more embodimentsof the present disclosure. The method may include one or moreoperations, functions, or actions as illustrated by one or more ofblocks 801-820. Although the blocks are illustrated in a sequentialorder, these blocks may be performed in parallel, and/or in a differentorder than those described herein. Also, the various blocks may becombined into fewer blocks, divided into additional blocks, and/oreliminated based upon the desired implementation. Although the method isdescribed in conjunction with motion enable system 100 of FIG. 1,persons skilled in the art will understand that any suitably configuredsystem is within the scope of the present disclosure. In the embodimentdescribed in conjunction with FIG. 8, the control algorithms for themethod steps reside in and/or are performed by controller 110. In otherembodiments, such control algorithms may reside in and/or be performedby any other suitable control circuit or computing device.

A method 800 begins at step 801, in which controller 110 receivescapacitive sensor active signal 102 from capacitive sensor 122, forexample when an operator moves a digit or other conductive object withina sensing region of capacitive sensor 122.

In step 802, controller 110 enables power connection 109 between powersource 140 and motor driver circuit 150. For example, in someembodiments, controller 110 transmits power enable signal 103 to powerenable switch 130.

In step 803, controller 110 receives mechanical switch active signal 101while still receiving capacitive sensor active signal 102. For example,controller 110 receives mechanical switch active signal 101 when theoperator depresses or actuates mechanical switch 121.

In step 804, in response to receiving mechanical switch active signal101 while still receiving capacitive sensor active signal 102,controller 110 controls a motion output of motor driver circuit 150 tofollow a targeted trajectory or velocity profile, for example viacontrol signal 104. The targeted trajectory or velocity profile can bedetermined based on various factors, such as which particular mechanicalswitch 121 has been depressed and for how long that particularmechanical switch 121 has been depressed.

In step 805, controller 110 determines whether the targeted trajectoryhas been completed, such as when the targeted trajectory is defined by apreprogrammed motion. If yes, method 800 proceeds to step 820 andterminates; if no, method 800 proceeds to step 806. Generally, step 805is performed while controller 110 controls the motion output of motordriver circuit 150 as described in step 804.

In step 806, controller 110 determines whether mechanical switch 121 isstill active. That is, controller 110 determines whether mechanicalswitch active signal 101 is still being received. If yes, method 800proceeds to step 807; if no, the operator is no longer depressing oractuating motion enable device 120, and method 800 proceeds to step 811.

In step 807, controller 110 determines whether capacitive sensor 122 isstill active. That is, controller 110 determines whether capacitivesensor active signal 102 is still being received. If yes, motion enabledevice 120 is operating properly and method 800 proceeds back to step804; if no, motion enable device 120 is not operating properly, since,capacitive sensor 122 should always be active when mechanical switch 121is active. Thus, when controller 110 determines in step 807 thatcapacitive sensor 122 is not active, a fault is detected and method 800proceeds to step 808.

In step 808, controller 110 reports the fault detected in step 807.Method 800 then proceeds to step 812 and a fast ramp down is performed,as shown. Alternatively, after controller 110 reports the detectedfault, the motion output of motor driver circuit 150 is stopped in someother suitable fashion, and method 800 proceeds directly to step 820 andterminates.

In step 811, which is performed in response to controller 110determining that mechanical switch 121 is no longer active, controller110 determines whether capacitive sensor 122 is still active. That is,controller 110 determines whether capacitive sensor active signal 102still being received. If yes, then the operator continues to hold adigit or other conductive object proximate motion enable switch 120, andmethod 800 proceeds to step 813 for a smooth ramp-down to be performed;if no, then the operator has completely removed the digit or conductiveobject from motion enable device 120, and method 800 proceeds to step812 for a fast ramp-down to be performed.

In step 812, controller 110 controls the output motion of motor drivercircuit 150 so that a fast ramp-down is performed. Typically, the fastramp-down is performed so that an IEC stopping distance for the actuatoror motor associated with motor driver circuit 150 is achieved. Method800 then proceeds to step 820 and terminates.

In step 813, controller 110 controls the output motion of motor drivercircuit 150 so that a smooth ramp-down is performed. Typically, thesmooth ramp-down is performed so that the actuator or motor associatedwith motor driver circuit 150 generates an output motion that follows anS-curve acceleration profile that reduces or eliminates jerk. Method 800then proceeds to step 820 and terminates.

In sum, embodiments described herein include a motion enablement systemthat meets IEC standards, including initiating motion of an associatedapparatus when two separate switches or control devices have beenactuated by the operator. In addition, the herein described motionenablement system is configured to stop motion of the associatedapparatus within an IEC stopping distances when the operator ceasesactuating both control devices. The motion enable system is furtherconfigured to minimize or otherwise reduce the potential for repetitivestress injuries in an operator.

While various aspects and embodiments have been disclosed herein, otheraspects and embodiments will be apparent to those skilled in the art.The various aspects and embodiments disclosed herein are for purposes ofillustration and are not intended to be limiting, with the true scopeand spirit being indicated by the following claims.

We claim:
 1. A motion-enable apparatus, comprising: a mechanical switchconfigured to enable a first signal when the mechanical switch isactuated from a first position to a second position, wherein the firstsignal indicates that the mechanical switch is in a first active state;and a capacitive sensor with a sensing region that is located adjacentto the mechanical switch, wherein the capacitive sensor is configured toenable a second signal when a user digit is disposed in the sensingregion, and wherein the second signal indicates that the capacitivesensor is in a second active state.
 2. The motion-enable apparatus ofclaim 1, wherein the mechanical switch comprises a button mechanism. 3.The motion-enable apparatus of claim 2, wherein the mechanical switch isactuated from the first position to the second position by beingdepressed.
 4. The motion-enable apparatus of claim 2, wherein themechanical switch includes a spring-return mechanism and is actuatedfrom the second position to the first position by the spring-returnmechanism.
 5. The motion-enable apparatus of claim 4, wherein the springreturn mechanism includes an elastic portion that is compressed when themechanical switch is depressed.
 6. The motion-enable apparatus of claim5, wherein the elastic portion includes a material that increases inelectrical conductivity when compressed.
 7. The motion-enable apparatusof claim 4, wherein the button mechanism comprises a recessed interfacesurface.
 8. The motion-enable apparatus of claim 1, wherein when themechanical switch is actuated to the second position, an electricalcircuit is closed.
 9. The motion-enable apparatus of claim 8, whereinthe electrical circuit transmits the first signal to a controller. 10.The motion-enable apparatus of claim 1, wherein the capacitive sensorenables the second signal by transmitting the second signal to acontroller.
 11. The motion-enable apparatus of claim 1, wherein thesensing region extends past an interface surface of the mechanicalswitch.
 12. The motion-enable apparatus of claim 11, wherein the sensingregion extends past the interface surface by at least about 2 mm and nomore than about 20 mm.
 13. The motion-enable apparatus of claim 11,wherein the interface surface is recessed from a surrounding surface ofthe mechanical switch.
 14. The motion-enable apparatus of claim 1,wherein the sensing region is positioned so that a user digit enters thesensing region before the user digit actuates the mechanical switch fromthe first position to the second position.
 15. A motion-enable system,comprising: an actuator; a mechanical switch that includes an interfacesurface and is configured to enable a first signal when the mechanicalswitch is actuated from a first position to a second position, whereinthe first signal indicates that the mechanical switch is in a firstactive state; a capacitive sensor with a sensing region that extendspast the interface surface of the mechanical switch, wherein thecapacitive sensor is configured to enable a second signal when aconductive object is disposed in the sensing region and the secondsignal indicates that the capacitive sensor is in a second active state,and a controller configured to: receive the second signal; whilereceiving the second signal, receiving the first signal; and in responseto receiving the first signal while receiving the second signal,enabling motion the actuator.
 16. The motion-enable system of claim 15,wherein the controller is further configured to, in response toreceiving the second signal, enabling a power connection to the motordriver circuit.
 17. The motion-enable system of claim 15, wherein thecontroller is further configured to, after transmitting the motionenable signal, controlling a motion output of the motor driver circuitto follow a targeted trajectory.
 18. The motion-enable system of claim15, wherein the capacitive sensor is configured with an extended sensingregion that extends beyond the sensing region that extends past theinterface surface.
 19. A method of enabling motion of an apparatus, themethod comprising: receiving a first signal from a capacitive sensorincluded in a motion enable device; while receiving the first signal,receiving a second signal from a mechanical switch included in themotion enable device; and in response to receiving the second signalwhile receiving the first signal, transmitting a motion enable signal toa motor driver circuit.